In the figure PQ is parallel to RS. The length of QT is 4 cm; the length of TS is 6 cm; the length of PQ is 10 cm. What is the length of RS?
TS : TQ = RS : PQ
6 : 4 = RS : 10
6 / 4 = RS / 10
60 / 4 = RS
RS = 15
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